Gap Analysis is part of Continual Service Improvement and compares the difference between expected service delivery and actual service delivery.
The difference is then analysed (Gap Analysis) in which an improvement programme is put in place to address the shortfall.
Example – A configuration item designed to provide an IT service no longer meets the needs of the business as a result of increased demand being placed upon it. Upgrading the configuration item so that expected service delivery can be achieved is required.

For me continual service improvement is about improving services already meeting expectations. narrowing the gap between expected and actual service is more like corrective action.

Your example ought to be addressed by capacity management and should not ever become a gap.

For me, gap analysis is a way of informing what has to be done to the current management system to achieve a new requirement, which could be taking on new services or meeting new legislation or to achieve an externally audited standard._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

template for what?_________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

I don't see how to have a useful template except for a gap analysis in a specific area.

You just list the components and qualities you want to be in place and check them off against your current state.

For ITSM, for example you could use an ISO20000 auditor check list, but it might be too high level._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718